Curing of coatings through ultraviolet (UV) radiation, thereby resulting in a coating for use as a gel (e.g. a hydrogel), requires efficient methods of initiating the chemical reaction responsible for the curing process. Cross-linking of polymeric material through generation of radical species upon irradiation with UV light is widely used to produce hydrogels for medical device coatings. Coating compositions with polyvinylpyrrolidone and a photoinitiator as the main constituents, which are cured with UV irradiation, are often used for producing hydrogels. The photoinitiators used in these processes can be either oligomeric or polymeric. Oligomeric photoinitiators are partially free to diffuse to the surface of the cured material, thereby rendering these substances exposed to the environment.
WO 2008/012325 and WO 2008/071796 describe photocuring of plastic coatings for medical devices.
Other published documents which relate to polymeric photoinitiators based on polyalkylethers are US 2007/0003588 and Xuesong Jiang et al, Polymer, 50 (2009) 37-41.